Wide irregular gaps to upvc windows

13 Sep 2011
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West Midlands
United Kingdom
hoping this is the right place for this quey, having removed the wallpaper to the window reveals, i've found wide and irregular gaps to the upvc windows of my parents house.

The gaps were bodged with lots of white silicone which i've now removed as we are intending on painting, so gaps look like the attached pic.

Can anyone suggest the best way of filling for painting - ie. can we just fill with unibond flexible decorators filler - i've never used it before but it says it can be painted but i'm worried that it says no need to sand means that you have to apply it perfectly with a trowel ?

ideally we'd like to just tak the filler right upto the upvc window frame without applying another bead of mastic at the junction.

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Can only access that pic through your profile, to be honest they look far to large for a flexi filler, it looks more like a job for a plasterer you could try asking them.

Looking at the picture, it would seem that the gaps/holes are little more than an inch wide. A flexible filler/caulk (cartridge type) is not suitable for this type of hole as it can be difficult to smooth out and will have a different texture to the surrounding plaster and so the repairs would always be noticeable.

You should be able to use a standard ready mixed or powder filler for the repairs which can be sanded smooth and will blend in much better. There is no reason why you can't finish tight to the window but it is always wise to use a bead of caulk or low modulus silicone around the frame to stop any perimeter cracking being caused by expansion/contraction of the frame.
Well the above might work I suppose yet taking another look at that pic it seems that a repair has already been attempted before and failed so I'm not really sure.

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thanks for the responses - have to confess was worried about the mismatch using flexible filler - unfortunately hiring a plasterer is out of the question (for budget reasons)

we've got some powder filler we can use for a smooth finish upto the window frame, but am worried that it would crack away, but i guess if i run a bead of decorators caulk at the junction that would hide the crack?

(from what i understand no previous repairs have been done - just the replacement upvc windows were siliconed against wallpaper and 2 layers of that polystyrene insulation layers/lining thus hiding the gaps)
The damage is pretty typical of new window installations and is often patched up (wrongly) by excessive amounts silicone. The polystyrene may have been acting as an insulation measure to try and combat a mould problem due to condensation which can be a problem around some windows. Most new uPVC windows now have trickle vents to help with this but if yours don't, and there are/were signs of mould, you may need to consider a method of dealing with it (good ventilation is always the best).

As said, you can use caulk to point the window frame, but personally, I prefer the low mod silicone as even caulk can crack/peel in some situations.
Well if I were honest I do have my doubts regarding a patch repair here being anything more than cosmetic, yet I hope it works out fine for you.

I have not seen your picture, but could you use 25mm wide uPVC strip cut to length? Window installers often do this when there is a large gap. The strips are inly about 5mm thick and often have a radius on one edge - the other edge butts upto the window. They adhere with silicone or super glue.
Thanks, that an interesting fallback option - will try to fill and if it looks bad will go with the cover strip (it looks like they used that trick on the ground floor)

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